1. Field of the Invention
The invention relates to an ophthalmoscope having a housing in which there are arranged an observing unit and an illuminating unit between which there are/is arranged diaphragm means and/or filter means that can be set via a swivel lever means mounted outside on the housing.
2. Description of the Background Art
U.S. Pat. No. 4,684,227 discloses a generic binocular ophthalmoscope in whose lower housing part an observing unit is arranged by means of which an examiner can examine through a patient's pupil. An illuminating unit with a light source is accommodated in the upper housing part. An adjustable diaphragm is arranged between the light source and the observing unit. Also provided is a filter means by means of which optical filters can be moved into the illuminating path between the illuminating source and the observing unit. For the purpose of setting the diaphragm and the optical filters, there is respectively mounted on the side of the housing swivel lever means that comprises a rotary element, arranged in a bearing opening, on the outside of which a swivel lever is fastened. The swivel levers are kinematically connected to a mechanism for setting the diaphragm and/or the optical filters.
The swivel lever means are mounted in a freely rotatable fashion in the bearing openings. As a rule, ophthalmoscopes are used by a single investigator who prefers a specific setting of the diaphragms and/or the optical filters. Other settings are carried out only rarely. Since the swivel lever means are supported in a freely rotatable fashion, the diaphragm or the optical filters are, however, displaced when the swivel levers are lightly touched, and this quickly comes about during improper handling. It is then necessary to reset the diaphragm and filters.